Rail heat treatment devices have been developed that cool high-temperature rails after hot rolling. For example, a rail heat treatment device includes a device for supporting and restraining a base of a rail to be cooled, a cooling header for jetting a cooling medium to the rail supported and restrained by the supporting and restraining device, and an oscillation mechanism for oscillating (reciprocating) the supporting and restraining device or the cooling header in the longitudinal direction of the rail (refer to Patent Literatures 1 and 2).
In the rail heat treatment devices disclosed in Patent Literatures 1 and 2, a plurality of cooling headers for cooling an underside portion of the base of the rail are arranged under a rail supporting position. The cooling headers are arranged in a discontinuous state with predetermined intervals along the longitudinal direction of the rail. Such a gap portion (hereinafter, referred to as a discontinuous portion) between the cooling headers generates a rail portion to which the cooling medium from the cooling header is not sufficiently applied in the rail to be cooled. As a result, uneven cooling of the rail occurs along the longitudinal direction of the rail. To avoid such uneven cooling of the rail, the cooling header jets the cooling medium to the rail to be cooled while the oscillation mechanism relatively oscillates the rail and the cooling header along the longitudinal direction of the rail.
In addition to the heat treatment technique for rails disclosed in Patent Literatures 1 and 2, examples of a conventional cooling method using oscillation include a cooling method for steel materials that includes a plurality of cooling nozzles in a conveying direction of the steel materials arranged therein, and jets the cooling medium from the cooling nozzles while relatively oscillating the cooling nozzles and the steel materials in the horizontal direction (refer to Patent Literature 3). The oscillation control described in Patent Literature 3 prevents supercooling of the steel materials immediately under the cooling nozzle and insufficient cooling of the steel materials at the middle of the cooling nozzle.